Contacts for vaporizers employed in vacuum metallizing



C. F. DUPUIS June 4, 1968 CONTACTS FOR VAPORIZERS EMPLOYED IN VACUUM METALLIZING Filed Oct. 8, 1965 INVENTOR CLYDE F Du PUIS i'fTORNEYS United States Patent 3,387,116 CONTACTS FOR VAPORIZERS EMPLOYED IN VACUUM METALLIZING Clyde F. Dupuis, Downers Grove, [1]., assignor to Continental Can Company, Inc., New York, N.Y., a corporation of New York Filed Oct. 8, 1965, Ser. No. 494,059 17 Claims. (Cl. 219-541 ABSTRACT OF THE DISCLOSURE Disclosed herein are contact provisions for coupling a high current resistive heater between supply conductors including a pair of contact blocks rigidly affixed to the conductors in conductive relation thereto. Each of the contact blocks include aligned apertures into which are inserted projection portions of contact collars having facing transverse surfaces for contacting corresponding transverse surfaces on the heater to be employed. One of said contact blocks has afiixed thereto a yoke portion including an adjustable member movable toward and away from the aperture formed therein to move the collar portion slidably located in that aperture via resilient means located between the adjustable member and the aperture mounted collar portion. Movement of the adjustably mounted member allows removal of the heater without disturbance of the positioning of the contact blocks and provides maintenance of the heater between the two collar surfaces through a heavy compressive load applied to the heater.

This invention relates to electrical contacts and more specifically to a means for coupling a resistance heater capable of high current capacity between a pair of electrical bus bars.

In many industrial operations, it is a requirement that components of high current capabilities be coupled across electrical means for supplying the high current, such as bus bars. One such application is in the vapor deposition of metals wherein a resistance heater is coupled between a pair of bus bars, the heater being formed to receive, and in many instances retain, metal in its solid state and through the heat generated as a result of current passage, cause the metal to be transformed into its moltened and vapor state. In other words, the heater or vaporizing element is employed for the purpose of raising the deposition material to a high temperature, i.e., above its vaporization or sublimation temperature at low pressures which are usually employed during the deposition process. The electrical resistance of the heater or vaporizing element produces an IR drop across the element so that the high current passing through the heater results in sufiicient heat being generated to raise the temperature of the heater to the desired temperature for accomplishing the vaporizing process.

The deleterious effects of high currents and the subsequent oxidation, erosion, etc. of the contacts is well known. For example, carbides and oxides of the metal are formed at the interface of the contact and the bus bar to such an extent that local heating, arcing, and generally reduced efficiency occurs. In many instances, it is necessary to adjust the voltage being applied to the heater or vaporizing element in order to assure a sufiicient current which will produce a heating effect appropriate to maintain the heater at the requisite temperature for evaporation and subsequent deposition of the metal.

The degradation of the contacts produces much down time of the equipment since the corroded contacts and heaters must be periodically replaced. The frequency of replacement contributes to the over-all inetficiency of the system. Further, if the contacts and heaters cannot be quickly replaced, then the loss of time contributes further to the decreased efliciency. Accordingly, if high current carrying contacts used for resistance heaters in many operations are to be truly successful, the contacts must permit a long and useful life of both the contacts and the Vaporizers or heaters coupled therebetween and, in the event that the contacts or heaters must be replaced after a long and useful life, the replacement must be accomplished in a very short time with little down time of the apparatus.

Accordingly, it is the principal object of the present invention to improve electrical contacts capable 'of high current capacities.

It is a further object of the present invention to extend the life of electrical contacts employed in resistance heaters, the heat being generated by the conduction of a high current through the resistance.

It is a further object of the present invention to reduce the time required for replacing the heating element or the contacts themselves, in high current carrying environments.

It is a further object of the present invention to reduce electrical losses in high current carrying conductors and contacts due to the deterioration of the points of contacts between such conductors and contacts.

It is a still further object of the present invention to prevent arcing between bus bars and contacts and between contacts and electrical resistance heaters in high current carrying elements.

These and other objects of the present invention are accomplished by providing a first contact block and a second contact block, each of the contact blocks having at least an aperture surrounded by a flat surface for engaging the fiat surface of its respective contact pin. Each contact pin is removable from its respective contact block and is formed of a cylindrical portion which mates with the aperture in the contact block and a flat rectangular section that abuts, on one side, the area of the contact block adjacent the aperture, and on its other side, the resistance heater. The first contact block is secured to its respective bus bar by any suitable means, such as by studs, bolts, etc.

The second contact block is substantially similar to the first contact block and is secured by any suitable means to its respective bus bar. However, the second contact block includes means coupled thereto for varying the compressive load applied to the resistance heater positioned between the pair of contact pins in engagement with the contact blocks. A yoke or plate member is positioned and secured to one side of the second contact block and on a side opposite to the side at which the resistance heater is positioned. A plunger is positioned within the aperture formed in the second contact block to receive one of the contact pins and in engagement with the pin. A stud or bolt is in threaded engagement with the yoke and in axial alignment with the plunger and contact pin. A resilient means, such as a coil spring, resiliently couples the stud to the plunger. Rotation of the stud, in one direction, will compress the spring and thereby force the plunger into firmer engagement with the contact pin supporting the resistance heater. The resistance heater is supported by a pair of contact pins which are in turn supported by the contact blocks. In this manner, rotation of the stud will apply an axial load to the first contact pin, the resistance heater and the second contact pin in engagement with the other contact block.

The resistance heater takes the form of a U-shaped channel for receiving the metal to be vaporized and, through the cooperation of the contact pins which close the ends of the resistance heater, any molten metal is retained in the trough so formed during its transition from the solid to the vapor state.

ice

The invention both as to its organization and method of operation together with further objects and advantages thereof will best be understood by reference to the following specification taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a perspective view of the invention and illustrating the contact blocks and the contact pins supporting the resistance heater therebetween;

FIGURE 2 is an elevational view, partly in section, and taken along the line 22 of the FIGURE 1;

FIGURE 3 is an elevational view with the resistance heater in section and taken along the line 33 of the FIGURE 1;

FIGURE 4 is a perspective view of a contact pin; and,

FIGURE 5 is a perspective view of the resistance heater.

With reference to the FIGURE 1, a bus bar is illustrated and supporting a first contact block 12. The bus bar 10 and the contact block 12 would usually be of copper and the contact block 12 would normally be of the water-cooled type although such is not necessary for the practice of the invention. The flat mating surfaces of the bus bar 10 and the first contact block 12 are maintained in position by a pair of bolts 14 and 16which are positioned in suitable apertures drilled into the contact block 12 and as shown in the FIGURE 2, the bolts 14 and 16 (only the bolt 14 is visible in the FIGURE 2) extend into the bus bar 10 so as to effect a rigid positioning of the first contact bar 12 with respect to the bus bar 10. The first contact block 12 has an opening or aperture 18 formed therein and substantially transverse to the general direction of the bus bar 10. The aperture 18 receives one end of a contact pin 59 which will be described with reference to the FIGURE 4.

As shown in the FIGURE 4, the contact pin 59 includes a cylindrical projection 60 joined to a collar 64. The cylindrical projection 60 of the contact pin 59 mates with the apertures 18 (and 18') in the contact blocks 12 (and 22) and the flat collar 60 abuts the contact block 12 in the flat area adjacent the aperture. The invention employs two substantially similar contact pins 59 and 59'.

A resistance heater 20 is shown in the FIGURE 5 and is shaped so as to form a trough for retaining molten metal. More specifically, the resistance heater 20 may be several inches in length and includes a longitudinal body portion 21, an upwardly turned flange 56 along one edge of the body portion 21 and a substantially parallel and similar upwardly turned flange 58 along the other edge. Through the cooperation of the flanges 56 and 58, the resistance heater, heats and holds any solid, liquid or a molten material. The solid metal would normally be introduced into the heater 20 in its wire form, by any suitable means (not shown).

The material from which the resistance heater 20 is constructed would be of a material having an impedance, at the frequency, voltage and current selected, sufficient to raise the temperature of the heater 2% above the vaporization point of the metal to be vaporized. Materials of this type include boron nitride, titanium diboride, silicon carbide, etc.

A contact block 22, known as the second contact block, is substantially similar in many respects to the first contact block 12 and is secured to a second bus bar 24 by the bolts 14' and 16'. In a similar manner, the contact block 22 has an aperture or opening 26 formed therein for receiving the cylindrical projection 60 of the contact pin 59'. However, certain difierences between the contact blocks 12 and 22 are apparent in that the contact block 22 supports the means for applying an axial compressive load to the resistance heater20 and the contact pins 59 and 59.

As shown in the FIGURES 1 and 2, a yoke 28 is formed of a pressure block 30 which may be of steel and of flat construction. The pressure block 30 is positioned away from the contact block 22 by a pair of rectangular spacers 32 and 34. Apertures are formed in the pressure block 30, the spacers 32 and 34 and the second contact block 22 so as to receive a pair of bolts 36 and 38, to maintain the yoke 28 in the position as shown. Preferably, the bolts 36 and 38 and their-respective apertures are formed near the outer edges of the pressure block 30. The bolts 36 and 38 are threaded into the contact block 22 so as to retain the yoke 28 in rigid position with respect to the contact block 22.

A threaded aperture 40 is centrally located in the pressure block 30 and in substantial alignment with the opening or aperture 26 in the contact block 22. A stud 42 having a reduced unthreaded portion 44 and a threaded portion 45 is in threaded engagement with the threaded aperture 40. A plunger 46 is positioned within the aperture 26 of the contact block 22 and from the end opposite to that which receives the contact pin 59'. The plunger 46 has a projection 48 of reduced diameter and of a diameter substantially equal to the unthreaded portion 44 of the stud 42. A coil spring 50 is positioned over the portion 44 of the stud 42 and the projection 48 and abuts the plunger 46 while a washer 52 is positioned on the stud 42 and about the portion 44. It will be understood that the washer 52 may be eliminated but is so illustrated as a matter of convenience. That is to say, the coil spring 50 could be so formed as to abut the flat shoulder formed by the reduction of the stud 42 to fashion the unthreaded portion 44.

As shown in the FIGURES 1 and 3, the stud 42, the Washer 52, the spring 50, the plunger 46, the contact pin 59', the heater 20 and the contact pin 59 are all in axial alignment with the contact pins 59 and 55'' positioned, respectively, in the apertures 18 and 26. The coil spring 50 resiliently urges the heater 20 into snug engagement with the contact pins 59 and 59' as Well as the contact pins 59 and 59' into their respective contact blocks 12 and 22.

The FIGURE 3 is an elevational view and illustrating the contact block 22 supported upon its bus bar 24 and maintained in position by the bolts 14 and 16. The bus bar 24 is tapped at 70 and 72 so as to receive, respectively, the bolts 16' and 14. The resistance heater 20 is illustrated with the body portion 21, the flange 56 and the flange 58 being shown in cross-section. The collar 64' of the contact pin 59' is visible While the cylindrical projection 60 is illustrated in dotted outline. The bolts 14, 14', 1-6 and 16' are threaded into their respective bus bars 19 and 24 in such a manner so as to pro vide a tight fit and thereby reduce electrical losses.

In assembling the apparatus set forth and in practicing the invention illustrated, the contact block 22 would be secured to the bus bar 24 by the bolts 14' and 16. The yoke 28 would be assembled in the manner shown by securing the bolts 36 and 38 in place. The stud 42 would be rotated so as to move it leftwardly as viewed in the FIGURE 2 so that the position of the plunger 46 would permit the subsequent positioning of the resistance heater 20. In like manner, the contact block 12 would be secured to the bus bar 10 by the bolts 14 and 16. The contact pin 59 is inserted in the aperture 18 of the Contact block 12 and the contact pin 59' is inserted in the aperture 26 of the contact block 22.

Next, the resistance heater 20 is positioned between the contact pins 59 and 59', it being understood that the position of the plunger 46, the spring 50 and the stud 42 permitting the positioning. While maintaining the heater 20 in the position best shown in the FIGURE 2, the stud 42 would be rotated so as to move it rightwardly and through the cooperation of the spring 50, force the tapered section 68 of the plunger 46 into firm engagement with the cylindrical portion 60 of the contact pin 59'. As continued rotational motion is applied to the stud 42, the collar 64 will seat against the contact block 12 about the aperture 18 and generally indicated at 74. Rotation of the stud 41 would be continued until firm engagement is accomplished between the surfaces 74 and the tapered section 68 of the plunger 46 so that the electrical resistance between the contact blocks 12 and 22 becomes only that of the contact pins 59 and 59' and the resistance heater 20, the contact resistance between the contact blocks 12 and 22 and the contact pins 59 and 59 having been reduced substantially to zero.

The compressional force exerted by the contacts of the present invention on the resistance heater takes advantage of the fact that heaters of this type have several times more resistance to compressional force than to flexural forces. The invention provides contacts which are a great improvement over contacts of the prior art, the most important reasoning being the extended heater life. The present invention also provides a great saving in labor in that the contact blocks are bolted to their respective bus bars and the bus bars and contact blocks remain in place whenever an operator replaces a heater. In the practice of the invention, the contact blocks 12 and 22 never lose good electrical contact with their respective bus bars so that arcing and inefiicient operation are eliminated or substantially reduced.

It will be apparent to those skilled in the art that variations and modifications of the invention are contemplated. For example, the heating means and contact pins may be formed as a unitary structure, i.e., cast or molded as a single piece. In addition, the apertures in the contact blocks could be extended upwardly or outwardly to form slots so that the heating means or heater and contact pins are move-d into the slots for positioning. Also, a contact pin may be formed on just one end of said heater, the other end of the heater fitting directly into a contact block aperture.

Thus, the present invention may be embodied in other specific forms without departing from the spirit and the essential characteristics of the invention. The present embodiment is, therefore, to be considered in all respects as illustrative and the scope of the invention being indicated by the appended claims rather than the foregoing description, and all changes which come Within the meaning and range of the equivalency of the claims are, therefore, intended to be embraced therein.

What is claimed is:

1. Means for coupling a heating means between a first and a second electrical conductor comprising first and second contact blocks positioned, respectively, upon said first and second electrical conductors, first and second heater contact means, an aperture formed in each of said blocks for receiving the ends of said heater contact means, abutment surface means formed on said first heater contact means and adapted for contact with said first block exteriorly of the aperture therein and means movably mounted in said aperture of said second block and in engagement with said second heater contact means for urging means for urging said abutment surface means formed on said first heater contact means into firm engagement with said first block.

2. Means for compressively coupling an elongated resistance heating means between first and second electrical conductors comprising first and second contact blocks, means for connecting said blocks to their respective first and second conductors, at least one of said means for connecting permitting ready removal of at least one of said first and second contact blocks, first and second heater contact means, a transverse opening in each of said blocks for receiving at least a portion of said first and second heater contact means, means formed on said first heater means and adapted for contact with said first block exteriorly of the opening therein for limiting movement of said first heater contact means and means acting in said opening of said second block and in engagement with said second heater contact means for urging said means formed on said first heater contact means into firm engagement with said first block, said second heater contact means solely limiting movement of said means acting in said opening in one direction when said resistance heating means is coupled bet-ween said first and second conductors.

3. Means for coupling an elongated resistance heater between a first and a second electrical conductor comprising first and second contact blocks rigidly mounted, respectively, upon said first and second electrical conductors, an aperture formed in each of said blocks, a pair of collars positioned at opposed ends of said heater and adapted to to be received in said apertures, said collars having projecting means thereon, means movably supported by said second block and in axial alignment with said heater and said collars for urging one of said collars into firm engagement with said first block exterior- 1y about its respective aperture, said collars having opposed contact surfaces thereon for contacting said resistance heater and applying force thereto only substantially parallel to the axis thereof to place said heater in compression.

4. Means for coupling an elongated resistance heater between a first and second electrical conductor comprising first and second contact blocks rigidly mounted, respectively, upon said first and second electrical conductors, an aperture formed in each of said blocks, means engaged by said heater and adapted for contact with said first block at said aperture, a yoke rigidly connected to said second block and on a side opposite to said heater, and adjustable means supported by said yoke and in engagement with said heater for adjustably urging said means engaged by said heater into firm engagement with said first block, said adjustable means comprising an element mounted by said second block for movement parallel to the longitudinal axis of said heater and adjustable bias means extending from said yoke to said element, said heater limiting axial movement of said element under the influence of said bias means.

5'. Means for coupling an elongated resistance heating means between a first and a second electrical conductor comprising first and second contact blocks positioned, "respectively, upon said first and second electrical conductors, an aperture formed in each of said blocks, means engaged by said heating means and adapted for contact with said first block at said aperture, a yoke connected to said second block and on a side opposite to said heating means, a plunger extending into said aperture of said second block, a cap screw in threaded engagement with said yoke and aligned with said plunger and means for resiliently coupling said cap screw to said plunger to thereby cause said plunger to engage said heating means and thereby urge said means engaged by said heater into firm engagement with said first block.

6. The combination as defined in claim 5 wherein said means for resiliently coupling is a coil spring.

7. Means for coupling an elongated resistance heating means between a first and a second electrical conductor comprising first and second contact blocks positioned, respectively, upon said first and second electrical conductors, an aperture formed in each of said blocks, a collar having a projection atfixed thereto and positioned in said aperture of said first block, said collar being adapted to abut said heating means, a yoke connected to said second block and on a side opposite to said heating means, a plunger extending into said aperture of said second block, a cap screw in threaded engagement with said yoke and aligned with said plunger, and a coil spring for resiliently.

in said aperture of said first block for abutting said heating means on a surface thereof transverse to the longitudinal axis of said heating means, a pressure plate supported by and away from said second block and on a side of the block opposite to said heating means, cooperating first and second transverse stop surfaces on said first block and said collar, and means cooperating with said pressure plate and a transverse surface of said heating means for urging said stop surface of said collar against said stop surface of said first block to thereby apply a compressive force to said heating means substantially axially thereto.

9. The combination as defined in claim 8 wherein said means cooperating are an axially aligned stud, spring and plunger, said stud being in threaded engagement with said plate and said plunger in engagement with said heating means.

10. Means for coupling an elongated resistance heating means between a first and a second electrical conductor comprising first and second contact blocks positioned, respectively, upon said first and second electrical conductors, an aperture formed in each of said blocks, restraining means supported juxtaposed one end of said heating means and adapted to contact with said first block exteriorly about its aperture and force exertive means supported by said second block and in abutting engagement with said heating means through said aperture of said second block for urging said restraining means into engagement with said first block and thereby control the compressive load imparted to said heating means, said heating means being maintained between said restraining means and said force exertive means solely by compressive forces thereon.

11. Means for coupling to a bus bar having a surface comprising a block having a mating surface for engagement with the surface of the bus bar, mounting means for rigidly mounting said block on said bus bar, a transverse aperture formed in said block, a yoke connected to a side surface of said block, plunger means positioned within said aperture for sliding within said aperture without restriction by said aperture, a stud in threaded engagement with said yoke and aligned with said plunger, and force exertive means extending between said stud and said plunger means, said plunger means having a contact surface generally transverse to the longitudinal axis of said aperture.

1'2. The combination as defined in claim 11 wherein said force exertive means is a resilient means.

13. The combination as defined in claim 11 wherein said means for coupling is a coil spring.

14. Means for coupling to a bus bar having a flat surface comprising a block having a flat surface for engagement with the flat surface of the bus bar, means for rigidly retaining the flat surfaces in engagement, a transverse opening formed in said block, pressure plate means supported by and away from a side surface of said block exteriorly of said aperture, and an axially aligned stud, spring and plunger, said stud supported by said plate and said plunger being positioned within said opening and in abutting relation with said pressure plate means, said spring joining said stud and plunger.

15. The combination as defined in claim 14 including means on said stud and cooperating with said plate for varying the position of said plunger in said opening.

16. Means for coupling a resistance heating means between a first and a second electrical conductor comprising first conductive contact block means rigidly, conductively mounted upon said first conductor, second conductive contact block means rigidly, conductively mounted upon said second conductor, said first contact block means comprising first conductive contact surface means having a contact face facing said second contact block means for conductively contacting a transverse surface on said heating means and for preventing longitudinal movement thereof, second conductive contact surface means slidably mounted by said second contact block means for movement toward and away from said first contact block means and having a second contact face thereon for conductively contacting a further transverse surface on said heating means, adjustable force exertive means on said second contact block means for moving said second contact surface means in sliding relation to said second contact block means and for applying an axial force to said heating means to tightly compress and support said heating means between said first and second contact surfaces.

17. The combination according to claim 16 wherein said second contact block means comprises an aperture formed therein, said second contact surface means being slidably received in said aperture and extending outwardly therefrom toward said first contact block means for moving said second contact face in the area bet-ween said first and second contact block means to permit removal and replacement of said heater means without movement of said first and second contact block means.

References Cited UNITED STATES PATENTS 412,449 10/1889 Askew 338-416 994,447 6/1911 Egly 338316 1,797,712 3/1931 Brodnax et a1. 219541 2,571,422 10/1951 Cole et al. 33 8-316 2,632,078 3/1953 Baxter et a1. 338-316 3,249,675 5/1966 Matchen 1325 FOREIGN PATENTS 7 115,882 7/1926 Switzerland. 954,397 4/ 1964 Great Britain.

RICHARD M. WOOD, Primary Examiner.

V. Y. MAYEWSKY, Examiner. 

